[vsnet-grb-info 3004] GRB 060121: HST observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4841
SUBJECT: GRB 060121: HST observations
DATE:    06/02/28 01:02:32 GMT
FROM:    Andrew Levan at U.of Leicester  <anl at star.le.ac.uk>

A.J. Levan, N.R. Tanvir (University of Hertfordshire), A. Fruchter
(STScI), J. Fynbo, J. Hjorth (Dark Cosmology Centre), E. Rol
(University of Leicester), D. Bersier (Liverpool JMU), J. Gorosabel,
A.J. Castro-Tirado (IAA-CSIC Granada) report for a larger collaboration:

We observed the location of the HETE-2 short hard burst GRB 060121
(Prigozhin et al. GCN 4551; Malesani et al. GCN 4561) with HST on 27
February 2006 using both ACS and NICMOS. Approximately 4500 s of
observations in each of F606W and F160W were obtained. Performing
astrometry between these images and those obtained at the WIYN (Levan et
al. GCN 4562) reveals no evidence for an afterglow to R>28, although the
position of the burst lies close to a faint red galaxy with F160W =24.0,
F606W =26.8. The morphology of the galaxy is long and thin, possibly an
edge on disk. If this object is the host galaxy of GRB 060121 then it is
relatively red compared to the hosts of long bursts, and there are also
several other galaxies with very red colours within 30" of the burst
position. Short bursts have been observed in a greater variety of
host galaxies, but in this case, the faintness of the galaxy in both the
optical and IR favour a higher redshift than has been measured for most
short bursts to date (which is also consistent with the red colour of the
afterglow).

We thank Matt Mountain for using Director's Discretionary Time to observe
GRB 060121.

Further analysis is ongoing.